Inertial Sensors can detect and measure various types of acceleration, tilt, shock, vibration, rotation, and multiple degrees-of-freedom motion, which can be used in industrial, medical, communications, consumer and automotive applications. To help provide motion detection and measurement, these sensors include accelerometers and gyroscopes.
Some Inertial Rate Sensors (IRSs), such as vibratory gyroscopes, can sense rotation when a driven oscillation of one or more vibratory members is coupled to another mode of the structure due the Coriolis Effect. A typical tuning fork gyroscope, for example, can sense rotation by using tines as vibratory members. Tuning fork gyroscopes typically have two tines, but other types of vibratory gyroscopes can have a different number of vibratory members. When the tines are driven in oscillation, a rotation about an axis parallel to the longitudinal axis (i.e., elongated dimension) of the tines can couple the driven oscillation into an anti-phase, out-of-plane motion of the tines. In other words, the tines move up and down out of the plane of the tuning fork gyroscope, out-of-phase with each other. This mode of oscillation is often called the sense mode (or pickup mode) of the tuning fork gyroscope. The axis about which rotation can be sensed is called the sensitive axis (or input axis).
Although oscillations of such an IRS enable the IRS to sense rotation, the oscillations also can introduce unwanted displacement in a mount of the IRS. For example, a vibratory gyroscope can be substantially balanced for motion along the axis of oscillatory movement, but can have unbalanced motion in the other axes. In particular, stresses at and/or near the crotch regions connecting the vibratory members can cause the rest of the structure to undergo motion perpendicular to the axis of oscillatory movement. Such unwanted displacement can negatively impact the stability and accuracy of an IRS.